The present invention relates to a character imaging system, the term "character" being used herein to refer to a letter of the alphabet, a numeral or other symbol.
More particularly, the invention is concerned with a system in which a selected one of a plurality of different such characters arrayed as windows in an otherwise opaque mask is projected optically onto a selected location on a working surface.
One important application for the present invention is in a system for marking a workpiece by means of laser light. The term "light" as used throughout this specification and claims is intended to cover not only visible light, but also infra-red and ultra violet light. High energy, pulsed (or continuous wave) coherent light is projected sequentially through selected character-defining windows in a mask to burn an impression of such characters into a workpiece. In known such system, either the workpiece is moved, or the beam is deflected by movement of the optical system, so that a word or sentence is written on the workpiece.
Another application of the present invention resides in the formation of words or messages that are projected onto a surface such as photographic film, or a screen, or on a larger scale, onto a wall, or even the side of a building, e.g. to provide a visual display. In these applications the light need not be coherent light. These latter applications of the invention nevertheless maintain the basic feature that the displayed message is generated by projecting a beam sequentially through different selected windows in a mask to spell out the message.